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Sauce

Onion Sauce

A sauce made from boiled onions, milk thickened with flour, seasoned with pepper and salt.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
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Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Onion Sauce

Ingredients

Directions

Prepare the onions

  1. Boil the onions in sufficient water until tender.

  2. Chop the onions finely.

Make the sauce

  1. Thicken the boiling milk with flour.

  2. Season the sauce with pepper and salt.

  3. Add the chopped onions to the sauce and simmer for five minutes.

Recipe from a historical cookbook (Internet Archive).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

  1. Onion + peppertop 11% of all pairs
    Smell alikemoderate
    Cooked together68,474 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

  2. Milk + flourtop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Onion + flourtop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Flour + peppertop 19% of all pairs
    Smell alikemoderate
    Cooked together50,459 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  5. Onion + milktop 20% of all pairs
    Smell alikemoderate
    Cooked together13,418 recipes

    Shared aroma: hexanal (green, grassy).

Milk and flour barely smell alike, yet cooks put them together in 78,219 recipes: they work on texture and structure more than aroma.

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Onions
Provide the bulk and mild sweetness that give the sauce its body and flavour.
Milk
Forms the liquid base of the sauce and adds richness and creaminess.
Flour
Thickens the boiling milk, giving the sauce its smooth, coating texture.

The step that matters

Thickening the boiling milk with flour. Flour must be stirred in evenly so its starch can swell and thicken the milk without forming lumps. Adding it to hot milk while stirring helps the starch disperse before it sets.

Swap the onion

How well each one fits the dish's main ingredients (milk, flour, pepper):

  1. Capsicumfits better
  2. Arrowrootfits better
  3. Potatofits better
  4. Onionthe original

Fit is the average pairing score against milk, flour, pepper. Candidates are from the same food group and used in at least 100 recipes.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.

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